/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.commons.udf.builtin;

import org.apache.iotdb.commons.exception.MetadataException;
import org.apache.iotdb.commons.udf.utils.UDFDataTypeTransformer;
import org.apache.iotdb.tsfile.file.metadata.enums.TSDataType;
import org.apache.iotdb.udf.api.UDTF;
import org.apache.iotdb.udf.api.access.Row;
import org.apache.iotdb.udf.api.access.RowWindow;
import org.apache.iotdb.udf.api.collector.PointCollector;
import org.apache.iotdb.udf.api.customizer.config.UDTFConfigurations;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameterValidator;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameters;
import org.apache.iotdb.udf.api.customizer.strategy.SlidingSizeWindowAccessStrategy;
import org.apache.iotdb.udf.api.customizer.strategy.SlidingTimeWindowAccessStrategy;
import org.apache.iotdb.udf.api.exception.UDFException;
import org.apache.iotdb.udf.api.exception.UDFInputSeriesDataTypeNotValidException;
import org.apache.iotdb.udf.api.exception.UDFParameterNotValidException;
import org.apache.iotdb.udf.api.type.Type;

import java.io.IOException;

/**
 * For each sliding window, M4 returns the first, last, bottom, top points. The window can be
 * controlled by either point size or time interval length. The aggregated points in the output
 * series has been sorted and deduplicated.
 *
 * <p>SlidingSizeWindow usage Example: "select M4(s1,'windowSize'='10','slidingStep'='10') from
 * root.vehicle.d1" (windowSize is required, slidingStep is optional.)
 *
 * <p>SlidingTimeWindow usage Example: "select
 * M4(s1,'timeInterval'='25','slidingStep'='25','displayWindowBegin'='0','displayWindowEnd'='100')
 * from root.vehicle.d1" (timeInterval is required, slidingStep/displayWindowBegin/displayWindowEnd
 * are optional.)
 */
public class UDTFM4 implements UDTF {

    enum AccessStrategy {
        SIZE_WINDOW,
        TIME_WINDOW
    }

    protected AccessStrategy accessStrategy;
    protected TSDataType dataType;

    public static final String WINDOW_SIZE_KEY = "windowSize";
    public static final String TIME_INTERVAL_KEY = "timeInterval";
    public static final String SLIDING_STEP_KEY = "slidingStep";
    public static final String DISPLAY_WINDOW_BEGIN_KEY = "displayWindowBegin";
    public static final String DISPLAY_WINDOW_END_KEY = "displayWindowEnd";

    @Override
    public void validate(UDFParameterValidator validator) throws UDFException {
        validator
                .validateInputSeriesNumber(1)
                .validateInputSeriesDataType(0, Type.INT32, Type.INT64, Type.FLOAT, Type.DOUBLE);

        if (!validator.getParameters().hasAttribute(WINDOW_SIZE_KEY)
                && !validator.getParameters().hasAttribute(TIME_INTERVAL_KEY)) {
            throw new UDFParameterNotValidException(
                    String.format(
                            "attribute \"%s\"/\"%s\" is required but was not provided.",
                            WINDOW_SIZE_KEY, TIME_INTERVAL_KEY));
        }
        if (validator.getParameters().hasAttribute(WINDOW_SIZE_KEY)
                && validator.getParameters().hasAttribute(TIME_INTERVAL_KEY)) {
            throw new UDFParameterNotValidException(
                    String.format(
                            "use attribute \"%s\" or \"%s\" only one at a time.",
                            WINDOW_SIZE_KEY, TIME_INTERVAL_KEY));
        }
        if (validator.getParameters().hasAttribute(WINDOW_SIZE_KEY)) {
            accessStrategy = AccessStrategy.SIZE_WINDOW;
        } else {
            accessStrategy = AccessStrategy.TIME_WINDOW;
        }

        dataType =
                UDFDataTypeTransformer.transformToTsDataType(validator.getParameters().getDataType(0));
    }

    @Override
    public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations)
            throws MetadataException {
        // set data type
        configurations.setOutputDataType(UDFDataTypeTransformer.transformToUDFDataType(dataType));

        // set access strategy
        if (accessStrategy == AccessStrategy.SIZE_WINDOW) {
            int windowSize = parameters.getInt(WINDOW_SIZE_KEY);
            int slidingStep = parameters.getIntOrDefault(SLIDING_STEP_KEY, windowSize);
            configurations.setAccessStrategy(
                    new SlidingSizeWindowAccessStrategy(windowSize, slidingStep));
        } else {
            long timeInterval = parameters.getLong(TIME_INTERVAL_KEY);
            long displayWindowBegin =
                    parameters.getLongOrDefault(DISPLAY_WINDOW_BEGIN_KEY, Long.MIN_VALUE);
            long displayWindowEnd = parameters.getLongOrDefault(DISPLAY_WINDOW_END_KEY, Long.MAX_VALUE);
            long slidingStep = parameters.getLongOrDefault(SLIDING_STEP_KEY, timeInterval);
            configurations.setAccessStrategy(
                    new SlidingTimeWindowAccessStrategy(
                            timeInterval, slidingStep, displayWindowBegin, displayWindowEnd));
        }
    }

    @Override
    public void transform(RowWindow rowWindow, PointCollector collector)
            throws UDFException, IOException {
        switch (dataType) {
            case INT32:
                transformInt(rowWindow, collector);
                break;
            case INT64:
                transformLong(rowWindow, collector);
                break;
            case FLOAT:
                transformFloat(rowWindow, collector);
                break;
            case DOUBLE:
                transformDouble(rowWindow, collector);
                break;
            default:
                // This will not happen
                throw new UDFInputSeriesDataTypeNotValidException(
                        0,
                        UDFDataTypeTransformer.transformToUDFDataType(dataType),
                        Type.INT32,
                        Type.INT64,
                        Type.FLOAT,
                        Type.DOUBLE);
        }
    }

    public void transformInt(RowWindow rowWindow, PointCollector collector) throws IOException {
        if (rowWindow.windowSize() > 0) { // else empty window do nothing
            int firstValue = rowWindow.getRow(0).getInt(0);
            int lastValue = rowWindow.getRow(rowWindow.windowSize() - 1).getInt(0);

            int minValue = Math.min(firstValue, lastValue);
            int maxValue = Math.max(firstValue, lastValue);
            int minIndex = (firstValue < lastValue) ? 0 : rowWindow.windowSize() - 1;
            int maxIndex = (firstValue > lastValue) ? 0 : rowWindow.windowSize() - 1;

            for (int i = 1; i < rowWindow.windowSize() - 1; i++) {
                int value = rowWindow.getRow(i).getInt(0);
                if (value < minValue) {
                    minValue = value;
                    minIndex = i;
                }
                if (value > maxValue) {
                    maxValue = value;
                    maxIndex = i;
                }
            }

            Row row = rowWindow.getRow(0);
            collector.putInt(row.getTime(), row.getInt(0));

            int smallerIndex = Math.min(minIndex, maxIndex);
            int largerIndex = Math.max(minIndex, maxIndex);
            if (smallerIndex > 0) {
                row = rowWindow.getRow(smallerIndex);
                collector.putInt(row.getTime(), row.getInt(0));
            }
            if (largerIndex > smallerIndex) {
                row = rowWindow.getRow(largerIndex);
                collector.putInt(row.getTime(), row.getInt(0));
            }
            if (largerIndex < rowWindow.windowSize() - 1) {
                row = rowWindow.getRow(rowWindow.windowSize() - 1);
                collector.putInt(row.getTime(), row.getInt(0));
            }
        }
    }

    public void transformLong(RowWindow rowWindow, PointCollector collector) throws IOException {
        if (rowWindow.windowSize() > 0) { // else empty window do nothing
            long firstValue = rowWindow.getRow(0).getLong(0);
            long lastValue = rowWindow.getRow(rowWindow.windowSize() - 1).getLong(0);

            long minValue = Math.min(firstValue, lastValue);
            long maxValue = Math.max(firstValue, lastValue);
            int minIndex = (firstValue < lastValue) ? 0 : rowWindow.windowSize() - 1;
            int maxIndex = (firstValue > lastValue) ? 0 : rowWindow.windowSize() - 1;

            for (int i = 1; i < rowWindow.windowSize() - 1; i++) {
                long value = rowWindow.getRow(i).getLong(0);
                if (value < minValue) {
                    minValue = value;
                    minIndex = i;
                }
                if (value > maxValue) {
                    maxValue = value;
                    maxIndex = i;
                }
            }

            Row row = rowWindow.getRow(0);
            collector.putLong(row.getTime(), row.getLong(0));

            int smallerIndex = Math.min(minIndex, maxIndex);
            int largerIndex = Math.max(minIndex, maxIndex);
            if (smallerIndex > 0) {
                row = rowWindow.getRow(smallerIndex);
                collector.putLong(row.getTime(), row.getLong(0));
            }
            if (largerIndex > smallerIndex) {
                row = rowWindow.getRow(largerIndex);
                collector.putLong(row.getTime(), row.getLong(0));
            }
            if (largerIndex < rowWindow.windowSize() - 1) {
                row = rowWindow.getRow(rowWindow.windowSize() - 1);
                collector.putLong(row.getTime(), row.getLong(0));
            }
        }
    }

    public void transformFloat(RowWindow rowWindow, PointCollector collector) throws IOException {
        if (rowWindow.windowSize() > 0) { // else empty window do nothing
            float firstValue = rowWindow.getRow(0).getFloat(0);
            float lastValue = rowWindow.getRow(rowWindow.windowSize() - 1).getFloat(0);

            float minValue = Math.min(firstValue, lastValue);
            float maxValue = Math.max(firstValue, lastValue);
            int minIndex = (firstValue < lastValue) ? 0 : rowWindow.windowSize() - 1;
            int maxIndex = (firstValue > lastValue) ? 0 : rowWindow.windowSize() - 1;

            for (int i = 1; i < rowWindow.windowSize() - 1; i++) {
                float value = rowWindow.getRow(i).getFloat(0);
                if (value < minValue) {
                    minValue = value;
                    minIndex = i;
                }
                if (value > maxValue) {
                    maxValue = value;
                    maxIndex = i;
                }
            }

            Row row = rowWindow.getRow(0);
            collector.putFloat(row.getTime(), row.getFloat(0));

            int smallerIndex = Math.min(minIndex, maxIndex);
            int largerIndex = Math.max(minIndex, maxIndex);
            if (smallerIndex > 0) {
                row = rowWindow.getRow(smallerIndex);
                collector.putFloat(row.getTime(), row.getFloat(0));
            }
            if (largerIndex > smallerIndex) {
                row = rowWindow.getRow(largerIndex);
                collector.putFloat(row.getTime(), row.getFloat(0));
            }
            if (largerIndex < rowWindow.windowSize() - 1) {
                row = rowWindow.getRow(rowWindow.windowSize() - 1);
                collector.putFloat(row.getTime(), row.getFloat(0));
            }
        }
    }

    public void transformDouble(RowWindow rowWindow, PointCollector collector) throws IOException {
        if (rowWindow.windowSize() > 0) { // else empty window do nothing
            double firstValue = rowWindow.getRow(0).getDouble(0);
            double lastValue = rowWindow.getRow(rowWindow.windowSize() - 1).getDouble(0);

            double minValue = Math.min(firstValue, lastValue);
            double maxValue = Math.max(firstValue, lastValue);
            int minIndex = (firstValue < lastValue) ? 0 : rowWindow.windowSize() - 1;
            int maxIndex = (firstValue > lastValue) ? 0 : rowWindow.windowSize() - 1;

            for (int i = 1; i < rowWindow.windowSize() - 1; i++) {
                double value = rowWindow.getRow(i).getDouble(0);
                if (value < minValue) {
                    minValue = value;
                    minIndex = i;
                }
                if (value > maxValue) {
                    maxValue = value;
                    maxIndex = i;
                }
            }

            Row row = rowWindow.getRow(0);
            collector.putDouble(row.getTime(), row.getDouble(0));

            int smallerIndex = Math.min(minIndex, maxIndex);
            int largerIndex = Math.max(minIndex, maxIndex);
            if (smallerIndex > 0) {
                row = rowWindow.getRow(smallerIndex);
                collector.putDouble(row.getTime(), row.getDouble(0));
            }
            if (largerIndex > smallerIndex) {
                row = rowWindow.getRow(largerIndex);
                collector.putDouble(row.getTime(), row.getDouble(0));
            }
            if (largerIndex < rowWindow.windowSize() - 1) {
                row = rowWindow.getRow(rowWindow.windowSize() - 1);
                collector.putDouble(row.getTime(), row.getDouble(0));
            }
        }
    }
}
